﻿using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;

/// <summary>
/// Vista style of FolderBrowserDialog
/// </summary>
public class OpenFolderDialog {
    #region Public Property
    public string DirectoryPath { get; set; }
    public bool? ShowDialog(Window owner = null) {
        ;
        IntPtr hwndOwner = owner != null ? new WindowInteropHelper(owner).Handle : Process.GetCurrentProcess().MainWindowHandle;
        IFileOpenDialog dialog = (IFileOpenDialog)new FileOpenDialog();
        try {
            IShellItem item;
            if (!string.IsNullOrEmpty(DirectoryPath)) {
                uint atts = 0;
                if (SHILCreateFromPath(DirectoryPath, out IntPtr idl, ref atts) == 0)
                    if (SHCreateShellItem(IntPtr.Zero, IntPtr.Zero, idl, out item) == 0)
                        dialog.SetFolder(item);
            }
            dialog.SetOptions(FOS.FOS_PICKFOLDERS | FOS.FOS_FORCEFILESYSTEM);
            uint hr = dialog.Show(hwndOwner);
            if (hr == ERROR_CANCELLED)
                return false;
            if (hr != 0)
                return null;
            dialog.GetResult(out item);
            item.GetDisplayName(SIGDN.SIGDN_FILESYSPATH, out string path);
            DirectoryPath = path;
            return true;
        } finally {
            Marshal.ReleaseComObject(dialog);
        }
    }
    #endregion

    #region BaseType
    [DllImport("shell32.dll")]
    private static extern int SHILCreateFromPath([MarshalAs(UnmanagedType.LPWStr)] string pszPath, out IntPtr ppIdl, ref uint rgflnOut);
    [DllImport("shell32.dll")]
    private static extern int SHCreateShellItem(IntPtr pidlParent, IntPtr psfParent, IntPtr pidl, out IShellItem ppsi);
    private const uint ERROR_CANCELLED = 0x800704C7;
    [ComImport]
    [Guid("DC1C5A9C-E88A-4dde-A5A1-60F82A20AEF7")]
    private class FileOpenDialog {
    }
    [ComImport]
    [Guid("42f85136-db7e-439c-85f1-e4075d135fc8")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IFileOpenDialog {
        [PreserveSig]
        uint Show([In] IntPtr parent); // IModalWindow
        void SetFileTypes();  // not fully defined
        void SetFileTypeIndex([In] uint iFileType);
        void GetFileTypeIndex(out uint piFileType);
        void Advise(); // not fully defined
        void Unadvise();
        void SetOptions([In] FOS fos);
        void GetOptions(out FOS pfos);
        void SetDefaultFolder(IShellItem psi);
        void SetFolder(IShellItem psi);
        void GetFolder(out IShellItem ppsi);
        void GetCurrentSelection(out IShellItem ppsi);
        void SetFileName([In, MarshalAs(UnmanagedType.LPWStr)] string pszName);
        void GetFileName([MarshalAs(UnmanagedType.LPWStr)] out string pszName);
        void SetTitle([In, MarshalAs(UnmanagedType.LPWStr)] string pszTitle);
        void SetOkButtonLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszText);
        void SetFileNameLabel([In, MarshalAs(UnmanagedType.LPWStr)] string pszLabel);
        void GetResult(out IShellItem ppsi);
        void AddPlace(IShellItem psi, int alignment);
        void SetDefaultExtension([In, MarshalAs(UnmanagedType.LPWStr)] string pszDefaultExtension);
        void Close(int hr);
        void SetClientGuid();  // not fully defined
        void ClearClientData();
        void SetFilter([MarshalAs(UnmanagedType.Interface)] IntPtr pFilter);
        void GetResults([MarshalAs(UnmanagedType.Interface)] out IntPtr ppenum); // not fully defined
        void GetSelectedItems([MarshalAs(UnmanagedType.Interface)] out IntPtr ppsai); // not fully defined
    }
    [ComImport]
    [Guid("43826D1E-E718-42EE-BC55-A1E261C37BFE")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    private interface IShellItem {
        void BindToHandler(); // not fully defined
        void GetParent(); // not fully defined
        void GetDisplayName([In] SIGDN sigdnName, [MarshalAs(UnmanagedType.LPWStr)] out string ppszName);
        void GetAttributes();  // not fully defined
        void Compare();  // not fully defined
    }
    private enum SIGDN : uint {
        SIGDN_DESKTOPABSOLUTEEDITING = 0x8004c000,
        SIGDN_DESKTOPABSOLUTEPARSING = 0x80028000,
        SIGDN_FILESYSPATH = 0x80058000,
        SIGDN_NORMALDISPLAY = 0,
        SIGDN_PARENTRELATIVE = 0x80080001,
        SIGDN_PARENTRELATIVEEDITING = 0x80031001,
        SIGDN_PARENTRELATIVEFORADDRESSBAR = 0x8007c001,
        SIGDN_PARENTRELATIVEPARSING = 0x80018001,
        SIGDN_URL = 0x80068000
    }
    [Flags]
    private enum FOS {
        FOS_ALLNONSTORAGEITEMS = 0x80,
        FOS_ALLOWMULTISELECT = 0x200,
        FOS_CREATEPROMPT = 0x2000,
        FOS_DEFAULTNOMINIMODE = 0x20000000,
        FOS_DONTADDTORECENT = 0x2000000,
        FOS_FILEMUSTEXIST = 0x1000,
        FOS_FORCEFILESYSTEM = 0x40,
        FOS_FORCESHOWHIDDEN = 0x10000000,
        FOS_HIDEMRUPLACES = 0x20000,
        FOS_HIDEPINNEDPLACES = 0x40000,
        FOS_NOCHANGEDIR = 8,
        FOS_NODEREFERENCELINKS = 0x100000,
        FOS_NOREADONLYRETURN = 0x8000,
        FOS_NOTESTFILECREATE = 0x10000,
        FOS_NOVALIDATE = 0x100,
        FOS_OVERWRITEPROMPT = 2,
        FOS_PATHMUSTEXIST = 0x800,
        FOS_PICKFOLDERS = 0x20,
        FOS_SHAREAWARE = 0x4000,
        FOS_STRICTFILETYPES = 4
    }
    #endregion
}